Add support for SHTC3 Temperature and Humidity sensor.

CMakeLists.txt

@@ -109,6 +109,7 @@ add_executable(fanpico
   src/i2c_dps310.c
   src/i2c_mcp9808.c
   src/i2c_pct2075.c
+  src/i2c_shtc3.c
   src/i2c_stts22h.c
   src/i2c_tmp102.c
   src/i2c_tmp117.c

src/i2c.c

@@ -73,6 +73,11 @@ void* pct2075_init(i2c_inst_t *i2c, uint8_t addr);
 int pct2075_start_measurement(void *ctx);
 int pct2075_get_measurement(void *ctx, float *temp, float *pressure, float *humidity);
 
+/* i2c_shtc3.c */
+void* shtc3_init(i2c_inst_t *i2c, uint8_t addr);
+int shtc3_start_measurement(void *ctx);
+int shtc3_get_measurement(void *ctx, float *temp, float *pressure, float *humidity);
+
 /* i2c_stts22h.c */
 void* stts22h_init(i2c_inst_t *i2c, uint8_t addr);
 int stts22h_start_measurement(void *ctx);
@@ -99,6 +104,7 @@ static const i2c_sensor_entry_t i2c_sensor_types[] = {
 	{ "DPS310", dps310_init, dps310_start_measurement, dps310_get_measurement },
 	{ "MCP9808", mcp9808_init, mcp9808_start_measurement, mcp9808_get_measurement },
 	{ "PCT2075", pct2075_init, pct2075_start_measurement, pct2075_get_measurement },
+	{ "SHTC3", shtc3_init, shtc3_start_measurement, shtc3_get_measurement },
 	{ "STTS22H", stts22h_init, stts22h_start_measurement, stts22h_get_measurement },
 	{ "TMP102", tmp102_init, tmp102_start_measurement, tmp102_get_measurement },
 	{ "TMP117", tmp117_init, tmp117_start_measurement, tmp117_get_measurement },
@@ -326,6 +332,46 @@ int i2c_write_register_u8(i2c_inst_t *i2c, uint8_t addr, uint8_t reg, uint8_t va
 }
 
 
+int i2c_read_raw(i2c_inst_t *i2c, uint8_t addr, uint8_t *buf, size_t len, bool nostop)
+{
+	int res;
+
+	DEBUG_PRINT("args=%p,%02x,%p,%u\n", i2c, addr, buf, len);
+
+	res = i2c_read_timeout_us(i2c, addr, buf, len, nostop,
+				I2C_READ_TIMEOUT(len));
+	if (res < len) {
+		DEBUG_PRINT("read failed (%d)\n", res);
+		return -2;
+	}
+
+	DEBUG_PRINT("read ok: %u\n", len);
+
+	return 0;
+}
+
+
+int i2c_write_raw_u16(i2c_inst_t *i2c, uint8_t addr, uint16_t cmd, bool nostop)
+{
+	uint8_t buf[2];
+	int res;
+
+	buf[0] = cmd >> 8;
+	buf[1] = cmd & 0xff;
+
+	DEBUG_PRINT("args=%p,%02x,%04x\n", i2c, addr, cmd);
+
+	res = i2c_write_timeout_us(i2c, addr, buf, 2, nostop,
+				I2C_WRITE_TIMEOUT(2));
+	if (res < 2) {
+		DEBUG_PRINT("write failed (%d)\n", res);
+		return -1;
+	}
+
+	return 0;
+}
+
+
 uint get_i2c_sensor_type(const char *name)
 {
 	int type = -1;
@@ -434,8 +480,8 @@ void setup_i2c_bus(struct fanpico_config *config)
 
 		res = i2c_init_sensor(v->i2c_type, v->i2c_addr, &ctx);
 		if (res) {
-			log_msg(LOG_NOTICE, "I2C Device %s (at 0x%02x): failed to initialize",
-				i2c_sensor_type_str(v->i2c_type), v->i2c_addr);
+			log_msg(LOG_NOTICE, "I2C Device %s (at 0x%02x): failed to initialize: %d",
+				i2c_sensor_type_str(v->i2c_type), v->i2c_addr, res);
 			continue;
 		}
 		config->i2c_context[i] = ctx;

src/i2c.h

@@ -75,6 +75,10 @@ int i2c_read_register_u16(i2c_inst_t *i2c, uint8_t i2c_addr, uint8_t reg, uint16
 int i2c_read_register_u8(i2c_inst_t *i2c, uint8_t i2c_addr, uint8_t reg, uint8_t *val);
 int i2c_write_register_u16(i2c_inst_t *i2c, uint8_t addr, uint8_t reg, uint16_t val);
 int i2c_write_register_u8(i2c_inst_t *i2c, uint8_t addr, uint8_t reg, uint8_t val);
+
+int i2c_read_raw(i2c_inst_t *i2c, uint8_t addr, uint8_t *buf, size_t len, bool nostop);
+int i2c_write_raw_u16(i2c_inst_t *i2c, uint8_t addr, uint16_t cmd, bool nostop);
+
 int32_t twos_complement(uint32_t value, uint8_t bits);
 
 

src/i2c_shtc3.c

@@ -0,0 +1,201 @@
+/* i2c_shtc3.c
+   Copyright (C) 2024 Timo Kokkonen <tjko@iki.fi>
+
+   SPDX-License-Identifier: GPL-3.0-or-later
+
+   This file is part of FanPico.
+
+   FanPico is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   FanPico is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with FanPico. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "pico/stdlib.h"
+#include "hardware/gpio.h"
+#include "hardware/i2c.h"
+
+#include "i2c.h"
+
+/* SHTC3 Commands */
+#define CMD_SLEEP              0xb098
+#define CMD_WAKEUP             0x3517
+#define CMD_MEASURE            0x58e0
+#define CMD_RESET              0x805d
+#define CMD_ID                 0xefc8
+
+#define SHTC3_DEVICE_ID        0x0807
+#define SHTC3_DEVICE_ID_MASK   0x083f
+
+
+typedef struct shtc3_context_t {
+	i2c_inst_t *i2c;
+	uint8_t addr;
+} shtc3_context_t;
+
+
+/* CRC-8 Lookup Table (Polymonial 0x31) */
+static const uint8_t shtc3_crc_lookup_table[] = {
+	0x00,0x31,0x62,0x53,0xC4,0xF5,0xA6,0x97,0xB9,0x88,0xDB,0xEA,0x7D,0x4C,0x1F,0x2E,
+	0x43,0x72,0x21,0x10,0x87,0xB6,0xE5,0xD4,0xFA,0xCB,0x98,0xA9,0x3E,0x0F,0x5C,0x6D,
+	0x86,0xB7,0xE4,0xD5,0x42,0x73,0x20,0x11,0x3F,0x0E,0x5D,0x6C,0xFB,0xCA,0x99,0xA8,
+	0xC5,0xF4,0xA7,0x96,0x01,0x30,0x63,0x52,0x7C,0x4D,0x1E,0x2F,0xB8,0x89,0xDA,0xEB,
+	0x3D,0x0C,0x5F,0x6E,0xF9,0xC8,0x9B,0xAA,0x84,0xB5,0xE6,0xD7,0x40,0x71,0x22,0x13,
+	0x7E,0x4F,0x1C,0x2D,0xBA,0x8B,0xD8,0xE9,0xC7,0xF6,0xA5,0x94,0x03,0x32,0x61,0x50,
+	0xBB,0x8A,0xD9,0xE8,0x7F,0x4E,0x1D,0x2C,0x02,0x33,0x60,0x51,0xC6,0xF7,0xA4,0x95,
+	0xF8,0xC9,0x9A,0xAB,0x3C,0x0D,0x5E,0x6F,0x41,0x70,0x23,0x12,0x85,0xB4,0xE7,0xD6,
+	0x7A,0x4B,0x18,0x29,0xBE,0x8F,0xDC,0xED,0xC3,0xF2,0xA1,0x90,0x07,0x36,0x65,0x54,
+	0x39,0x08,0x5B,0x6A,0xFD,0xCC,0x9F,0xAE,0x80,0xB1,0xE2,0xD3,0x44,0x75,0x26,0x17,
+	0xFC,0xCD,0x9E,0xAF,0x38,0x09,0x5A,0x6B,0x45,0x74,0x27,0x16,0x81,0xB0,0xE3,0xD2,
+	0xBF,0x8E,0xDD,0xEC,0x7B,0x4A,0x19,0x28,0x06,0x37,0x64,0x55,0xC2,0xF3,0xA0,0x91,
+	0x47,0x76,0x25,0x14,0x83,0xB2,0xE1,0xD0,0xFE,0xCF,0x9C,0xAD,0x3A,0x0B,0x58,0x69,
+	0x04,0x35,0x66,0x57,0xC0,0xF1,0xA2,0x93,0xBD,0x8C,0xDF,0xEE,0x79,0x48,0x1B,0x2A,
+	0xC1,0xF0,0xA3,0x92,0x05,0x34,0x67,0x56,0x78,0x49,0x1A,0x2B,0xBC,0x8D,0xDE,0xEF,
+	0x82,0xB3,0xE0,0xD1,0x46,0x77,0x24,0x15,0x3B,0x0A,0x59,0x68,0xFF,0xCE,0x9D,0xAC
+};
+
+static uint8_t crc8(uint8_t *buf, size_t len)
+{
+	uint8_t crc = 0xff;
+
+	for (int i = 0; i < len; i++) {
+		crc = shtc3_crc_lookup_table[crc ^ buf[i]];
+	}
+
+	return crc;
+}
+
+
+static int shtc3_read_u16(i2c_inst_t *i2c, uint8_t addr, uint16_t *val, bool nostop)
+{
+	uint8_t buf[3], crc;
+	int res;
+
+	DEBUG_PRINT("args=%p,%02x,%p\n", i2c, addr, val);
+
+	res = i2c_read_raw(i2c, addr, buf, 3, nostop);
+	if (res) {
+		DEBUG_PRINT("read failed (%d)\n", res);
+		return -1;
+	}
+
+	*val = (buf[0] << 8) | buf[1];
+	crc = crc8(buf, 2);
+	DEBUG_PRINT("read ok: [%02x %02x (%02x)] %04x (%u), crc=%02x\n", buf[0], buf[1], buf[2], *val, *val, crc);
+
+	if (crc != buf[2]) {
+		DEBUG_PRINT("checksum mismatch!\n");
+		return -2;
+	}
+
+	return 0;
+}
+
+
+void* shtc3_init(i2c_inst_t *i2c, uint8_t addr)
+{
+	int res;
+	uint16_t val = 0;
+	shtc3_context_t *ctx = calloc(1, sizeof(shtc3_context_t));
+
+	if (!ctx)
+		return NULL;
+	ctx->i2c = i2c;
+	ctx->addr = addr;
+
+
+	/* Read and verify device ID */
+	res = i2c_write_raw_u16(i2c, addr, CMD_ID, false);
+	if (res)
+		goto panic;
+	sleep_us(10);
+	res = shtc3_read_u16(i2c, addr, &val, false);
+	if (res)
+		goto panic;
+	if ((val & SHTC3_DEVICE_ID_MASK) != SHTC3_DEVICE_ID)
+		goto panic;
+
+
+	/* Reset sensor */
+	res = i2c_write_raw_u16(i2c, addr, CMD_RESET, false);
+	if (res)
+		goto panic;
+	sleep_us(250);
+
+
+	/* Read and verify device ID again... */
+	res = i2c_write_raw_u16(i2c, addr, CMD_ID, false);
+	if (res)
+		goto panic;
+	sleep_us(10);
+	res = shtc3_read_u16(i2c, addr, &val, false);
+	if (res)
+		goto panic;
+	if ((val & SHTC3_DEVICE_ID_MASK) != SHTC3_DEVICE_ID)
+		goto panic;
+
+	return ctx;
+
+panic:
+	free(ctx);
+	return NULL;
+}
+
+
+int shtc3_start_measurement(void *ctx)
+{
+	shtc3_context_t *c = (shtc3_context_t*)ctx;
+	int res;
+
+	/* Initiate measurement */
+	res = i2c_write_raw_u16(c->i2c, c->addr, CMD_MEASURE, false);
+	if (res)
+		return -1;
+
+	return 13;  /* measurement should be available after 12.1ms */
+}
+
+
+int shtc3_get_measurement(void *ctx, float *temp, float *pressure, float *humidity)
+{
+	shtc3_context_t *c = (shtc3_context_t*)ctx;
+	int res;
+	uint8_t buf[6];
+	uint16_t t_raw = 0;
+	uint16_t h_raw = 0;
+
+	/* Get Measurement */
+	res = i2c_read_raw(c->i2c, c->addr, buf, 6, false);
+	if (res)
+		return -1;
+
+	/* Check CRC of received values */
+	if (crc8(&buf[0], 2) != buf[2])
+		return -2;
+	if (crc8(&buf[3], 2) != buf[5])
+		return -3;
+
+	h_raw = (buf[0] << 8) | buf[1];
+	t_raw = (buf[3] << 8) | buf[4];
+	DEBUG_PRINT("h_raw = %u, t_raw = %u\n", h_raw, t_raw);
+
+	*temp = -45 + 175 * (double) t_raw / 65536;
+	*pressure = -1.0;
+	*humidity = 100 * (double) h_raw / 65536;
+	DEBUG_PRINT("temp: %0.1f, humidity: %0.1f\n", *temp, *humidity);
+
+	return 0;
+}
+
+